A liquid crystal active phased array antenna

Abstract

The present invention provides a liquid crystal active phased array antenna, comprising an antenna array unit (1); a first multi-layer substrate (2); a shielding-heat dissipation-waveguide metal cavity (3); a second multi-layer substrate (4), the second multi-layer substrate (4) integrating a radio frequency amplification module (5) and a heat conducting column (6); a heat dissipation gasket (7); a first glass substrate (16); a liquid crystal layer (9) located between the first glass substrate (16) and a second glass substrate (17); a liquid crystal phase shifter (10) located between the liquid crystal layer (9) and the second glass substrate (17); the second glass substrate (17); a third multi-layer substrate (8); and a waveguide power distribution network metal cavity (11) located below the third multi-layer substrate (8). The present invention solves the design difficulty of guiding the antenna metal ground of the liquid crystal phase shifter (10), applies an active module to the liquid crystal phase shifter (10), and reduces the system loss of the liquid crystal phase shifter (10) array antenna.

Description

Technical Field

[0001] The present invention relates to the technical field of phased array antennas, and more particularly to a liquid crystal active phased array antenna. Background Art

[0002] Each antenna unit at the back end of an active phased array includes a complete set of independent transceiver (T / R) components, which can control the formation of various radiation beams: high-gain single-beam radiation, multi-beam directional radiation, etc. Due to the independence of each unit, an active phased array can also be divided into multiple transceiver arrays for radar or communication, improving the flexibility of use compared to passive phased arrays.

[0003] The T / R components of traditional active phased arrays include a transmitting branch, a receiving branch, a radio frequency switch, and a phase shifter. Each T / R component has both a high-power amplifier (HPA), a filter, a limiter, a low-noise amplifier (LNA), an attenuator, a phase shifter, a beam control circuit, etc. Therefore, high cost and high power consumption are the main problems it faces.

[0004] In recent years, the progress of high-performance electromagnetic liquid crystal material technology has provided an effective solution for the design of low-cost and low-power phased array antennas. As a revolutionary technological innovation, liquid crystal phased array antenna technology has become the focus of research and development by many manufacturers. Currently, there are many technical problems in the design practice of liquid crystal phase shifters, such as large liquid crystal layer thickness resulting in large losses and long response time, etc.; for radio frequency signals, the feed network, antenna, active components, control power supply, etc. all require a metal ground. Under the existing process capabilities, to ensure the uniformity of the liquid crystal thickness, the liquid crystal can only be encapsulated in a cell between two glass substrates. And to effectively utilize the performance of the liquid crystal, the metal ground of the liquid crystal panel is usually placed on one of the substrates inside the cell, and the external connection of this metal ground is achieved by means of glass drilling. On the one hand, it is easy to have a liquid leakage phenomenon, reducing the yield rate; on the other hand, it is still very difficult to achieve the metalized glass vias in the process. Therefore, it is urgent to achieve non-contact grounding and then realize the multi-layer metal ground layout in the design of liquid crystal phased array antennas.

[0005] Although the liquid crystal phase shifter has significant advantages such as high FoM, high phase control accuracy, low power consumption, and low cost compared to traditional digital phase shifters, in practical applications, in order to improve performance indicators and design flexibility, liquid crystal phased array antennas sometimes need to adopt an active architecture design, introducing an active radio frequency amplification module (5) between the antenna and the phase shifter. However, due to the special structure of the liquid crystal phase shifter and the panel, it is impossible to directly weld the radio frequency amplification module (5) between the antenna and the phase shifter, which is also one of the main technical difficulties in the current field of liquid crystal phased array antenna design. Summary of the Invention

[0006] The object of the present invention is achieved by the following technical solutions.

[0007] To solve the above problems, the present invention combines a waveguide cavity and adds a grounded choke metal sheet (19) to solve the problem of external RF grounding in the glass substrate box. The short-circuit structure used in traditional waveguide-to-transmission line affects antenna radiation, and a multi-layer substrate can solve the problem of coexistence of the short-circuit structure and the antenna radiation patch.

[0008] The present invention provides a liquid crystal active phased array antenna, including, arranged in sequence from top to bottom:

[0009] An antenna array unit (1);

[0010] A first multi-layer substrate (2);

[0011] A shielding - heat dissipation - waveguide metal cavity (3);

[0012] A second multi-layer substrate (4), the second multi-layer substrate (4) integrating a radio frequency amplification module (5), a heat conducting column (6), and a heat dissipation gasket (7);

[0013] A first glass substrate (16);

[0014] A liquid crystal layer (9) located between the first glass substrate (16) and the second glass substrate (17); a liquid crystal phase shifter (10) located between the liquid crystal layer (9) and the second glass substrate (17);

[0015] A second glass substrate (17);

[0016] A third multi-layer substrate (8);

[0017] A waveguide power division network metal cavity (11) located below the third multi-layer substrate (8).

[0018] Further, the first multi-layer substrate (2) has conductive vias (15), conductive blind vias (13), and a first metal ground (12). The conductive vias (15) connect the antenna array unit (1) located on the top layer of the first multi-layer substrate (2) and the first transmission line located on the bottom layer of the first multi-layer substrate (2), and the conductive vias (15) do not contact the first metal ground (12).

[0019] Further, the first multi-layer substrate (2) is further provided with a first transmission line to waveguide structure (14). The first transmission line to waveguide structure (14) includes a transmission line, a matching line, a radiation patch, and a choke metal sheet (19); the conductive blind vias (13) inside the first multi-layer substrate (2) are located around the radiation patch of the first transmission line to waveguide structure (14) and are connected to the first metal ground (12) inside the first multi-layer substrate (2), but are not connected to the transmission line, the matching line, and the radiation patch.

[0020] Furthermore, the shielding - heat dissipation - waveguide metal cavity (3) is located below the first multilayer substrate (2), and shielding grooves and waveguide openings are formed around the heat dissipation gasket (7) and the radiation sheet of the first transmission line to waveguide structure (14).

[0021] Furthermore, the shielding groove of the shielding - heat dissipation - waveguide metal cavity (3) wraps the heat dissipation gasket (7), contacts the conductive blind hole (13) of the first multilayer substrate (2), but is not connected to the first transmission line, the matching line, and the radiation sheet. The center of the waveguide opening of the shielding - heat dissipation - waveguide metal cavity (3) is aligned with the center of the radiation sheet of the first transmission line to waveguide structure (14).

[0022] Furthermore, there are choke metal sheets (19) and conductive blind holes (13) for confining the electric field inside the second multilayer substrate (4).

[0023] Furthermore, the heat dissipation gasket (7) is located between the second multilayer substrate (4) and the shielding - heat dissipation - waveguide metal cavity (3), connecting the heat conduction column (6) to the shielding - heat dissipation - waveguide metal cavity (3).

[0024] Furthermore, the heat conduction column (6) is built inside the first glass substrate (16), connecting the heat dissipation gasket (7) to the RF amplification module (5).

[0025] Furthermore, the RF amplification module (5) is built inside the first glass substrate (16) for encapsulating the liquid crystal layer (9), realizing the integrated design of the liquid crystal encapsulation and the RF amplification module (5). There is a slotted second metal ground (18) at the bottom of the first glass substrate (16).

[0026] Furthermore, the liquid crystal phase shifter (10) unit is located on the top of the third multilayer substrate (8); the signal is coupled from the transmission line of the first waveguide to transmission line structure located on the second multilayer substrate (4) through the gap of the second metal ground (18) to the liquid crystal phase shifter (10) unit located on the top of the third multilayer substrate (8).

[0027] Furthermore, the first electrode of the liquid crystal phase shifter (10) unit is located between the second metal ground (18) and the liquid crystal layer (9), and the second electrode is located between the liquid crystal phase shifter (10) unit and the liquid crystal layer (9). The phase shift amount of the liquid crystal phase shifter (10) is controlled by controlling the voltage difference between the first electrode and the second electrode.

[0028] Furthermore, there are choke metal sheets (19) and conductive blind holes (13) for confining the electric field inside the third multilayer substrate (8).

[0029] Further, the second transmission line to waveguide structure is located at the bottom of the third multi-layer substrate (8), and includes a transmission line, a matching line, a radiation patch, and a choke metal sheet (19).

[0030] Further, the waveguide power division network metal cavity (11) is located below the third multi-layer substrate (8), and has the characteristics of single waveguide port input and multi-waveguide port output. The waveguide form is designed according to the required radio frequency signal power division ratio, and waveguide ports meeting the requirements are opened at the top of the cavity.

[0031] Further, the output waveguide port of the waveguide power division network metal cavity (11) is aligned with the center of the radiation patch of the second transmission line to waveguide structure.

[0032] The advantages of the present invention are as follows: The present invention integrates the radio frequency amplification module and the liquid crystal phased array antenna in an integrated manner, designs it inside the antenna panel structure, and it is easy to add a shielding structure to reduce the influence of the radio frequency amplification module on the antenna and the phase shifter. At the same time, the integrated design of shielding, heat dissipation, and waveguide also improves the space utilization rate. Description of the Drawings

[0033] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered as a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0034] Fig. Figure 1 shows a schematic structural diagram of a liquid crystal active phased array antenna according to an embodiment of the present invention;

[0035] Fig. 2(a) shows a top view of the phase shifter structure according to an embodiment of the present invention; Fig. 2(b) shows a side sectional view of the phase shifter structure according to an embodiment of the present invention. Fig. 2(c) is an equivalent circuit model of a specific embodiment of the present invention.

[0036] Fig. Figure 3 shows a side view of the transition of the liquid crystal microstrip to the upper waveguide according to an embodiment of the present invention;

[0037] Fig. Figure 4 shows a top view of the transition of the liquid crystal microstrip to the upper waveguide according to an embodiment of the present invention;

[0038] Fig. Figure 5 shows a side view of the transition of the liquid crystal microstrip to the lower waveguide according to an embodiment of the present invention;

[0039] Fig. Figure 6 shows a top view of the transition of the liquid crystal microstrip to the lower waveguide according to an embodiment of the present invention. Detailed Embodiments

[0040] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0041] The antenna of the present invention operates in the Ku band. Of course, those skilled in the art can know that it is also suitable for use in other frequency bands. The overall antenna is a multi-layer structure and will be described from top to bottom in conjunction with the accompanying drawings: As Figure 1 shown, a liquid crystal active phased array antenna includes, arranged in order from top to bottom: an antenna array unit (1); a first multi-layer substrate (2); a shielding - heat dissipation - waveguide metal cavity (3); a heat dissipation gasket (7); a second multi-layer substrate (4), and the second multi-layer substrate (4) integrates a radio frequency amplification module (5) and a heat conducting column (6); a first glass substrate (16); a liquid crystal layer (9) located between the first glass substrate (16) and the second glass substrate (17); a liquid crystal phase shifter (10) located between the liquid crystal layer (9) and the second glass substrate (17); a second glass substrate (17); a third multi-layer substrate (8); and a waveguide power distribution network metal cavity (11) located below the third multi-layer substrate (8).

[0042] The antenna array unit (1) is placed on the topmost layer of the entire antenna and is etched on the upper surface of the first multi-layer substrate (2). As Figure 3 shown, the lowermost layer of the first multi-layer substrate (2) is a microstrip feeding network for feeding the antenna on the topmost layer. There is a complete layer of metal between the antenna and the feeding network, which serves as the common ground for the upper - layer antenna and the lower - layer feeding network. It can completely isolate the transmission of radio frequency signals in the feeding network and the signal radiation of the antenna patch, improve the radiation efficiency of the antenna, and ensure that the radiation pattern of the antenna is closer to the theoretical value, facilitating subsequent beam synthesis and control. The signal transmission between the feeding network and the radiation patch can be achieved by means of coupling or direct connection with a probe, and corresponding design selections should be made according to different usage requirements.

[0043] The first multi-layer substrate (2) has conductive vias (15), conductive blind vias (13), and a first metal ground (12). The conductive vias (15) connect the antenna array unit (1) located on the top layer of the first multi-layer substrate (2) and the first transmission line located on the bottom layer of the first multi-layer substrate (2), and the conductive vias (15) do not contact the first metal ground (12).

[0044] As Figure 4As shown, a first transmission line to waveguide structure (14) is further provided inside the first multi-layer substrate (2). The first transmission line to waveguide structure (14) includes a transmission line, a matching line, a radiation patch, and a choke metal sheet (19). The conductive blind vias (13) inside the first multi-layer substrate (2) are located around the radiation patch of the first transmission line to waveguide structure (14) and are connected to the first metal ground (12) inside the first multi-layer substrate (2), but are not connected to the first transmission line, the matching line, or the radiation patch.

[0045] Closely attached below the first multi-layer substrate (2) is a shielding - heat dissipation - waveguide metal cavity (3). The main purpose is to transmit the signals of the feeding network to the module of the second multi-layer substrate (4). Using the waveguide metal cavity as the signal transmission medium not only shields the signal crosstalk between the top - layer antenna and the intermediate radio frequency amplification module (5), but also helps with the heat dissipation of the entire antenna. In addition, the hardness of the multi-layer substrate in the present invention is limited, and the intermediate waveguide metal cavity provides a certain support for the entire antenna structure, increasing the strength of the entire structure.

[0046] The shielding - heat dissipation - waveguide metal cavity (3) is located below the first multi-layer substrate (2). Shielding grooves and waveguide ports are opened around the heat dissipation gasket (7) and the radiation patch of the first transmission line to waveguide structure (14).

[0047] The shielding groove of the shielding - heat dissipation - waveguide metal cavity (3) wraps the heat dissipation gasket (7) and contacts the conductive blind vias (13) of the first multi-layer substrate (2), but is not connected to the first transmission line, the matching line, or the radiation patch. The center of the waveguide port of the shielding - heat dissipation - waveguide metal cavity (3) is aligned with the center of the radiation patch of the first transmission line to waveguide structure (14).

[0048] Inside the second multi-layer substrate (4), there are choke metal sheets (19) and conductive blind vias (13) for confining the electric field.

[0049] The radio frequency amplification module (5) is built inside the first glass substrate (16) for encapsulating the liquid crystal layer (9), realizing the integrated design of liquid crystal encapsulation and the radio frequency amplification module (5). There is a second metal ground (18) with a slit at the bottom of the first glass substrate (16).

[0050] The heat conducting columns (6) are built inside the first glass substrate (16) and connect the heat dissipation gasket (7) and the radio frequency amplification module (5).

[0051] The heat dissipation gasket (7) is located between the second multi-layer substrate (4) and the shielding - heat dissipation - waveguide metal cavity (3) and connects the heat conducting columns (6) and the shielding - heat dissipation - waveguide metal cavity (3).

[0052] The second multi-layer substrate (4) is located below the shielding-heat dissipation-waveguide metal cavity (3). Its upper surface is a radio frequency microstrip line that receives the radio frequency signal transmitted through the waveguide metal cavity. The metal probe conducts the signal into the radio frequency amplification module (5) in the lower layer. Figure 1 The radio frequency amplification module (5) is placed in the first glass substrate (16). The first multi-layer substrate (2), the second multi-layer substrate (4), and the second multi-layer substrate (4) can all be composed of one or several of materials such as silicon, glass, PCB, ceramic, sapphire, silicon carbide, etc., and are planar or curved. In this embodiment, as Figure 5 shown, the uppermost substrate of the third multi-layer substrate (8) and the lowermost substrate of the second multi-layer substrate (4) are both glass. Integrating the radio frequency amplification module (5) inside the glass improves the compactness of the structure of the present invention. During the use of the radio frequency amplification module (5), heat will be generated. In the present invention, a heat dissipation gasket (7) is added in the second multi-layer substrate (4) to conduct the heat generated by the radio frequency amplification module (5) to the waveguide metal cavity above, ensuring the heat dissipation performance and enabling it to work stably.

[0053] There are choke metal sheets (19) and conductive blind vias (13) for confining the electric field inside the third multi-layer substrate (8). As Figure 6 shown, the second transmission line to waveguide structure is located at the bottom of the third multi-layer substrate (8), including a transmission line, a matching line, a radiation sheet, and a choke metal sheet (19).

[0054] The liquid crystal phase shifter (10) unit is located at the top of the third multi-layer substrate (8); the signal is coupled from the transmission line of the first waveguide to transmission line structure located on the second multi-layer substrate (4) through the gap of the second metal ground (18) to the liquid crystal phase shifter (10) unit located at the top of the third multi-layer substrate (8).

[0055] As shown in Fig. 2(b), the first electrode of the liquid crystal phase shifter (10) unit is located between the second metal ground (18) and the liquid crystal layer (9), and the second electrode is located between the liquid crystal phase shifter (10) unit and the liquid crystal layer (9). The phase shift amount of the liquid crystal phase shifter (10) is controlled by controlling the voltage difference between the first electrode and the second electrode.

[0056] Fig. 2(c) is an equivalent circuit model of a specific embodiment of the present invention. 501 and 502 are equivalent inductances formed by the rectangular gap and the metal ground, 601 and 602 are equivalent capacitances formed by the feeder and the stub and the metal floor, and 603 is an equivalent adjustable capacitance formed by the feeder and the stub and the metal floor. By adjusting the dielectric constant of the metamaterial dielectric layer, the capacitance value of 603 can be changed, thereby changing the phase shift amount of the phase shifter.

[0057] The metal cavity (11) of the waveguide power divider network is located below the third multi-layer substrate (8). It has the characteristics of single waveguide port input and multi-waveguide port output. The waveguide form is designed according to the required power division ratio of the RF signal, and waveguide ports that meet the requirements are opened at the top of the cavity.

[0058] The output waveguide port of the metal cavity (11) of the waveguide power divider network is aligned with the center of the radiation patch of the second transmission line to waveguide structure.

[0059] The liquid crystal phase shifter (10) is one of the core technical means of the present invention. The liquid crystal is located between the lowermost glass substrate in the second multi-layer substrate (4) and the uppermost glass substrate in the third multi-layer substrate (8). Making a cell between the glasses and placing the liquid crystal is an existing mature process means, which ensures the feasibility of the present invention. In the present invention, the liquid crystal thickness, i.e., the cell thickness, is kept below 30 μm. The liquid crystal with a low cell thickness has a fast response speed. Only the phase shifter designed in this way can be used in the RF field. And the liquid crystal is driven by voltage, and the internal current is close to 0, so the driving power consumption is very low. Although the liquid crystal phase shifter (10) has significant advantages such as high FoM, high phase control accuracy, low power consumption, and low cost compared with traditional digital phase shifters, in practical applications, in order to improve the performance index and design flexibility, the liquid crystal phased array antenna sometimes needs to adopt an active architecture design, and an active RF amplification module (5) is introduced between the antenna and the phase shifter.

[0060] The surface circuit of the liquid crystal phase shifter (10) is located below the liquid crystal, and the metal ground is above the liquid crystal. Here, the metal ground isolates the crosstalk between the RF transmission signal and the antenna radiation signal again, and plays a certain isolation role for the RF signal of the RF amplification module (5), improving the integrity and consistency of the liquid crystal phase shifter (10). The metal ground is placed close to the liquid crystal to ensure the maximum utilization of the electrical properties of the liquid crystal. If the metal ground is placed on the upper layer of the glass above the liquid crystal, that is, there is a state-variable liquid crystal and a state-fixed glass between the surface circuit of the phase shifter and the metal ground. At this time, the change in the electrical properties of the liquid crystal will reduce the influence on the state of the phase shifter and decrease the phase shift amount. Therefore, there can only be one substance, the liquid crystal, between the surface circuit of the phase shifter and the metal ground. Since this layer of metal ground is placed above the liquid crystal and below the glass, and the glass cannot be drilled and it is difficult to lead out, a choke metal sheet (19) is added in combination with the waveguide cavity to solve the problem of difficult grounding of this layer of metal.

[0061] Below the liquid crystal phase shifter (10) is the third multi-layer substrate (8). The low cell thickness liquid crystal phase shifter (10) has a large loss, and the microstrip line with the liquid crystal as the substrate also has a large loss. Therefore, in order to reduce the loss, the signal of the phase shifter needs to be led down one more level. So the third multi-layer substrate (8) is introduced to transmit the signal of the phase shifter to the waveguide cavity power divider network metal cavity (11) at the bottom.

[0062] Embodiment phase shifter:

[0063] In the present invention, a fractal design method is adopted for the phase shifter, realizing a miniaturized structure of the phase shifter, enabling a phase shifter to be placed under each patch, and achieving full active control of the antenna. Using liquid crystal as the medium, the effect of changing the phase is achieved through voltage control.

[0064] As shown in Fig. 2(a), the specific implementation is to arrange metal traces on one side of the liquid crystal, including a main feeder, primary branches, and secondary branches; the other side is a metal ground, on which multiple rectangular slots are etched, including primary matching slots, primary transmission slots, secondary matching slots, and secondary transmission slots. The mutual arrangement of the branches and slots can adjust the inductance and capacitance, realize LC oscillation in the working frequency band, increase the phase difference between both ends of the main feeder, thereby achieving the purpose of miniaturization and reducing the loss on the premise of the same phase shift amount.

[0065] Embodiment of the transition from liquid crystal microstrip to upper waveguide:

[0066] As Figure 3 、 4 shown, first, the microstrip line under the liquid crystal is transferred to the microstrip line on the upper layer of the glass through the way of slot coupling; then the microstrip line on the upper layer of the glass is connected to the microstrip line on the upper layer of the second multi-layer substrate (4) through vias; the microstrip line on the upper layer of the second substrate is then converted into a microstrip waveguide. A set of grounding structures is included in the second layer substrate, that is, multiple metallized vias inside the second substrate in the figure form a grounding structure with a choke metal sheet (19) to ground, introducing the metal ground on the upper layer of the liquid crystal into the waveguide metal cavity to make it common ground.

[0067] Embodiment of the transition from liquid crystal microstrip to lower waveguide:

[0068] As Figure 5 、 6 shown, because there is no RF amplification module (5), the microstrip line under the liquid crystal here is directly connected to the microstrip line on the lower layer of the third substrate through slot coupling. There is no microstrip line under the middle glass. Different from the transition to the upper waveguide, the slot here is on the same side of the liquid crystal microstrip and the substrate microstrip, on the upper surface of the liquid crystal. Similarly, this structure also needs to lead out the metal ground on the upper layer of the liquid crystal, and use the grounding structure with a choke metal sheet (19) to lead out the ground.

[0069] The above is only a preferred specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A liquid crystal active phased array antenna, characterized in that, it includes, arranged successively from top to bottom: an antenna array unit (1); a first multi-layer substrate (2); a shielding - heat dissipation - waveguide metal cavity (3); a heat dissipation gasket (7); a second multi-layer substrate (4), and the second multi-layer substrate (4) integrates a radio frequency amplification module (5) and a heat conduction column (6); a first glass substrate (16); a liquid crystal layer (9) located between the first glass substrate (16) and a second glass substrate (17); a liquid crystal phase shifter (10) located between the liquid crystal layer (9) and the second glass substrate (17); a second glass substrate (17); a third multi-layer substrate (8); a waveguide power distribution network metal cavity (11) located below the third multi-layer substrate (8); a first transmission line to waveguide structure (14) is provided in the first multi-layer substrate (2), and the first transmission line to waveguide structure (14) includes a transmission line, a matching line, a radiation patch and a choke metal sheet (19); choke metal sheets (19) and conductive blind vias (13) for confining an electric field are inside the second multi-layer substrate (4); choke metal sheets (19) and conductive blind vias (13) for confining an electric field are inside the third multi-layer substrate (8).

2. The liquid crystal active phased array antenna according to claim 1, characterized in that, conductive vias (15), conductive blind vias (13) and a first metal ground (12) are inside the first multi-layer substrate (2), the conductive vias (15) connect the antenna array unit (1) located at the top layer of the first multi-layer substrate (2) and a first transmission line located at the bottom layer of the first multi-layer substrate (2), and the conductive vias (15) do not contact the first metal ground (12).

3. The liquid crystal active phased array antenna according to claim 2, characterized in that, the conductive blind vias (13) inside the first multi-layer substrate (2) are located around the radiation patch of the first transmission line to waveguide structure (14), are connected to the first metal ground (12) inside the first multi-layer substrate (2), but are not connected to the first transmission line, the matching line and the radiation patch.

4. The liquid crystal active phased array antenna according to claim 3, characterized in that, the shielding - heat dissipation - waveguide metal cavity (3) is located below the first multi-layer substrate (2), and shielding grooves and waveguide ports are formed around the heat dissipation gasket (7) and the radiation patch of the first transmission line to waveguide structure (14).

5. The liquid crystal active phased array antenna according to claim 4, characterized in that, the shielding groove of the shielding - heat dissipation - waveguide metal cavity (3) wraps the heat dissipation gasket (7), contacts the conductive blind vias (13) of the first multi-layer substrate (2), but is not connected to the first transmission line, the matching line and the radiation patch, and the center of the waveguide port of the shielding - heat dissipation - waveguide metal cavity (3) is aligned with the center of the radiation patch of the first transmission line to waveguide structure (14).

6. The liquid crystal active phased array antenna according to claim 1, characterized in that, The heat dissipation gasket (7) is located between the second multi-layer substrate (4) and the shielding-heat dissipation-waveguide metal cavity (3), connecting the heat conducting column (6) and the shielding-heat dissipation-waveguide metal cavity (3).

7. A liquid crystal active phased array antenna according to claim 1, wherein, The heat conducting column (6) is built inside the first glass substrate (16), connecting the heat dissipation gasket (7) and the radio frequency amplification module (5).

8. A liquid crystal active phased array antenna according to claim 1, wherein, The radio frequency amplification module (5) is built inside the first glass substrate (16) for encapsulating the liquid crystal layer (9), realizing the integrated design of liquid crystal encapsulation and the radio frequency amplification module (5). There is a second metal ground (18) with a slit at the bottom of the first glass substrate (16).

9. A liquid crystal active phased array antenna according to claim 1, wherein, The liquid crystal phase shifter (10) unit is located on the top of the third multi-layer substrate (8); the signal is coupled from the transmission line of the first waveguide-to-transmission line structure located on the second multi-layer substrate (4) through the slit of the second metal ground (18) to the liquid crystal phase shifter (10) unit located on the top of the third multi-layer substrate (8).

10. A liquid crystal active phased array antenna according to claim 9, wherein, The first electrode of the liquid crystal phase shifter (10) unit is located between the second metal ground (18) and the liquid crystal layer (9), and the second electrode is located between the liquid crystal phase shifter (10) unit and the liquid crystal layer (9). The phase shift amount of the liquid crystal phase shifter (10) is controlled by controlling the voltage difference between the first electrode and the second electrode.

11. A liquid crystal active phased array antenna according to claim 1, wherein, The second transmission line-to-waveguide structure is located at the bottom of the third multi-layer substrate (8), including a transmission line, a matching line, a radiation patch and a choke metal sheet (19).

12. A liquid crystal active phased array antenna according to claim 1, wherein, The waveguide power division network metal cavity (11) is located below the third multi-layer substrate (8), having the characteristic of single waveguide port input and multi-waveguide port output. The waveguide form is designed according to the required radio frequency signal power division ratio, and waveguide ports meeting the requirements are opened at the top of the cavity.

13. A liquid crystal active phased array antenna according to claim 11, wherein, The output waveguide port of the waveguide power division network metal cavity (11) is aligned with the center of the radiation patch of the second transmission line-to-waveguide structure.

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